The objectives of this project are to define and generate filarial proteins that are important in inducing parasite-specific immune responses in the human host and to understand, at a molecular level, the differences among related filarial species. Recombinant antigens and probes have been identified that a) encode immunoreactive and potentially protective molecules of W. bancrofti; b) can distinguish among related filarial species; c) identify repeated segments of the W. bancrofti, O. volvulus and Loa loa genome; d) are of potential diagnostic importance; and e) are responsible for the induction of immediate hypersensitivity type responses in filarial infections.